This invention relates to methods for producing a ball pivot arrangement for a ball joint in which the ball pivot arrangement has an essentially spherical upper region and an essentially bar-shaped lower region and to a corresponding ball pivot arrangement in which the spherical region is capable of being mounted in a joint cup or a joint socket to form a ball joint and the bar-shaped region constitutes a joint rod.
Conventional integrally produced ball pivot arrangements are generally cast, forged or rolled according to their shape. The blanks produced in this way have an essentially spherical upper region and an essentially bar-shaped lower region. In order to permit the ball pivot blank to be used appropriately in a ball joint, it has to be remachined after casting. Preferably, the ball pivot produced as a blank is lathe-turned, ground and/or hardened appropriately for the desired use. It is also possible for ball pivots of this type to be forged.
The conventional method for producing ball pivot arrangements which is ultimately used in a ball joint is not designed in the best possible way. On the one hand, the method is complicated and costly, since the ball pivot is first cast and the resulting blank then has to be remachined appropriately at a high expense. Remachining is made even more labor intensive by the non-uniform shape of the ball pivot structure. Furthermore, a disadvantage of the conventional ball pivot arrangement is that the spherical region and the bar-shaped region consist essentially of the same material or of the same alloy. Since the spherical region is generally capable of being mounted in a joint cup or joint socket of a ball joint and the bar-shaped region is generally designed as a joint rod, different forces with different stresses are applied to these differently shaped regions. In order to withstand these different stresses, for example, the spherical region has to be hardened in a different way from the bar-shaped region. This in turn makes the operation even more labor intensive. Also, a disadvantage of the conventional ball pivots is that it is not possible, for example, to produce the spherical region from a highly wear-resistant steel while using a less wear-resistant and possibly less expensive steel for the bar-shaped region. The production of conventional ball pivot arrangements thus becomes increasingly costly and complicated with increasing differences between the spherical region and the bar-shaped region as required for their respective uses.